@kurosa
Yes, muskets weren't really used large scale in battles in Europe before Tercio Squares were a thing, and then it was maybe 1/4 of the formation that had muskets (I think?) Before that they would've had arquebusiers on smaller scales, but due to the gunpowder they couldn't stand too close to eachother due to the danger (or atleast that's what I read somewhere)
Tercios dominated the european battlefield for... 100-200 years ? Something like that I think. But then Gustavus Adolphus came up with the swedish idea of line formation, which essentially meant they could have more muskets facing the enemy at the same time, compared to tercios in the same amount of area. I'm not really sure about the ratios for the swedish troops, but their tactics were very offensive. Get close enough for a volley, fire, then charge.
Though the development of firearms had a hand in the development of tactics to use them, I can't say which 'era' of tactics had which type of musket. Nor can I recognize the musket in this chapter for which particular type it is, which could explain which time in european military history you could compare it to and consider the tactics used then.
@AlmondMagnum
We can assume the firearms do more damage than bow, okay ? And we can assume they make more noise than bows, right ? Both of which would prove useful against demonic beasts